Eleclazine exhibits enhanced selectivity for long QT syndrome type 3-associated late Na+ current.

Abstract

BACKGROUND:

Eleclazine (GS-6615) is a sodium channel blocker designed to improve the selectivity for cardiac late Na+ current (INa) over peak INa.

OBJECTIVES:

The goals of this study were to investigate the inhibition of late INa by eleclazine using a sample of long QT syndrome type 3 (LQT3) and overlap LQT3/Brugada syndrome mutant channels; to compare the apparent binding rates for eleclazine with those for other class 1 antiarrhythmic agents; and to investigate the binding site.

METHODS:

Wild-type human cardiac voltage-gated sodium channel (hNaV1.5) and 21 previously reported variants were studied using patch clamp recordings from a heterologous expression system.

RESULTS:

Eleclazine inhibited anemone toxin II-enhanced late INa from wild-type hNaV1.5 with a drug concentration that causes 50% block of 0.62 ± 0.12 μM (84-fold selectivity over peak INa). The drug concentration that causes 50% block of eleclazine to inhibit the enhanced late INa from LQT3 mutant channels ranged from 0.33 to 1.7 μM. At predicted therapeutic concentrations, eleclazine and ranolazine inhibited peak INa to a similar degree as assessed with 4 overlap LQT3/Brugada syndrome mutations. Eleclazine was found to interact with hNaV1.5 significantly faster than ranolazine and 6 other class 1 antiarrhythmic agents. Engineered mutations (F1760A/Y1767A) located within the local anesthetic binding site decreased the inhibition of late INa and peak INa by eleclazine.

CONCLUSION:

At predicted therapeutic concentrations, eleclazine elicits potent inhibition of late INa across a cohort of NaV1.5 mutant channels. These properties are consistent with a class 1b antiarrhythmic agent that associates with unusually rapid binding/unbinding rates.

• Authors: Nesrine El-Bizri, Cheng Xie, Lynda Liu, James Limberis, Michael Krause, Ryoko Hirakawa, Steven Nguyen, Dennis R Tabuena, Luiz Belardinelli, Kristopher M Kahlig
• Journal: Heart rhythm (Heart Rhythm) Vol. 15 Issue 2 Pg. 277-286 (02 2018) ISSN: 1556-3871 [Electronic] United States
• PMID: 29017927 (Publication Type: Journal Article)
• Copyright: Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Chemical References

• Oxazepines
• Sodium Channel Blockers
• eleclazine

Topics

• Action Potentials
• Cardiac Conduction System Disease (drug therapy, metabolism, physiopathology)
• Humans
• Long QT Syndrome (drug therapy, metabolism, physiopathology)
• Myocytes, Cardiac (drug effects, metabolism, pathology)
• Oxazepines (therapeutic use)
• Patch-Clamp Techniques
• Sodium Channel Blockers (therapeutic use)